Golden caster sugar is made from beets or unrefined sugar cane and is a fine, granulated sugar. The sugar has a faint buttery flavor and is a pale brown in color. It is more common in the United Kingdom than in the United States.
Caster sugar can be found in the United States. It is very fine granulated sugar. The crystals dissolve quickly because they are so small, making this sugar perfect for creating meringues, mousses, custards and sweetening cold drinks. Castor sugar and superfine sugar are alternate names.
Golden caster sugar, however, is not as common in the U.S. as it is overseas. Many recipes call for this specific type of sugar, especially sponge cakes, shortbreads and macaroons. The sweetness of golden caster sugar and regular superfine sugar, however, is the same. Therefore, a chef can safely substitute white caster sugar in a recipe that calls for the golden, unrefined brand. The substitution ratio is a simple one to one, meaning if the recipe calls for one cup of the golden caster sugar, one can substitute one cup of white caster sugar. The only difference may be in a very subtle change of the buttery flavor or golden color of the finished product.